In the development of chronic obstructive pulmonary disease (COPD) there is a transition period when the individual is asymptomatic and the physician is unaware of the disorder. The present SCOR program includes a collaborative multidisciplinary approach to the study of obstructive lung disease especially during its earliest stages. In the first section of the program epidemiologic and physiologic approaches are applied to investigate the etiology, risk factors, and the natural history of airways obstruction. In the second section, immunologic and physiologic approaches are used to study acute reactions of the airways and their relation to chronic disease. In the third section, pathologic and physiologic approaches are applied to evaluate chronic reactions in the development of airways obstruction. Our goal is to characterize the individual at risk for COPD. With that knowledge, it may be possible to introduce effective modes of intervention.